Machining process



March 19, 1935. R. HLCRAMER ETAL 1,994,754

MACHINING PROCESS Filed Jhl 14, 19:52

INVENTORS: RAYMOND H CRAMER, JOHN G. MORRELL,

THEIR ATTORNEY March 19, 1 935.

R. H. CRAMER ET AL MACHINING PROCESS Filed July 14, 1952 FIG.5

INVENTORS; RAYMOND 1-1. CRAMER, JOHN 5. MORRELL,

fi fl $2 1M THEIR ATT'OFZNEY Patented Mar. 19, 1935 I v poration,Detroit, Micln, a corporation of Delaware Application ul 14', 1932,Serial No. 622,504 'IIClaims. (o1.51-2'zs) UNITED- STATES PATENT OFFICEThis invention relates to machining processes, the invention is notnecessarily limited to the especially thev grindingof,hollow articles,and I specific procedure disclosed for illustrative purcomprises all ofthe ieaturesandaspects of novposes in the accompanying drawing in whichelty herein disclosed, Heretofora inthe manu- Figs. 1 to 5 arediagrammatic views of grinding facture oia sleeve or"ring, for instance,it has machines showing several steps in the machining 5 been thepractice'togrind the -,.exterior surface of a hollow article. 1 i V ,ofthe rough articleasfnear as" possible to cir- In Fig. 1, a sleeve A orother rough article to cular form and size and then grind the bore bemachined to size is shown in grinding relaoi the article to the.desiredinternal diameter. tion to' a centerless grinding machine havinga Centerless' grinding 'machines [will produce a grindingwheel 6, aregulating wheel 8, and a piece that'is approximately round but internalWork support 10; This machine is utilized to grinding machines usingchucks, if'they produce] grind the external surface to round form but around bore, are not entirely satisfactory .ior only a part of the stockis removed of that needprecision work because of the difficulty of'cened to bring the piece to size. tering the piece and getting uniformwall thick- Referring, to Fig. 2, the article is then transness, thatis, concentricity of inner andouter' ferred to an internal grindingmachine, prefwalls. Improvement in this'lastrespect has more 'erably. achuckless machine having a series of rorecently been secured by the useof chuckless v tating wheels, one wheel 12 being a supporting internalgrinding machines but when the aridler, another wheel 13 being a drivenreguvticles are relativelyzt-hin-walled and heat treatlating wheel, athird wheel 14 being a pressure 20 ed, an out-of-rou'ndnessdevelops.This is probidler which holds the work against the other ably due to therelease ofinternal strains-by rewheels, and 16 being a grinding wheel.Wheels 'mov'al of stock and although the bad eifect may 13 and 16 andthe article have their centers on become'more or less neutralized if thesleeve a common line along which relative feeding 5 isafterwardsp'ressed into around housing, it is movement canbe produced ifdesired. Only a a desired to have a perfect article initially for allportion of the stock is removed of that needed to fuses. [1 v I bringthe piece to size.

--By the'presentinvention, precision is greatly According to Fig. 3, thearticle is then reincreased by-alternately removing stock in incregroundexternally on a centerless grinder havments from the outer and innersurfaces to grading a grinding wheel 18, a regulating wheel 20 30 uallybring the, piece to the desired size. Thus and a work support 22. Ofcourse this could be each surface istrued up 'afterthe removal of thesame machine used first but a second mastock from the other surface mayhave impaired chine having a finer abrasive wheel is preits shape and bydividing the stool; removed into ferred. Any small out-of-roundnessresulting stages, the out-of-round condition is so minifrom the releaseof strains during the internal mized that it disappears oris not ofconsequence. grinding operation is removed by this second Furthermore,the amount of stock removed at external grinding operation whichpreferably reeach out can conveniently'be made less and less moves anamount of stock which will bring the and with progressively finerabrasives, and small piece almost down to the desired external diammarksor marring that sometimes result from eter. Also any small marks ormarring'of the the high pressure contact of the work with the exteriorsurface, as from contact with the wheels driving wheels during a heavyout are eliminated. 12, 13 or 14, are likewise removed.

An object of the invention, aceordlngly, is to According to Fig. 4, thearticle is then reprovide an improved method of precision magroundinternally on an internal grinding machlning of hollow articles. Anotherobject is to chine su h as that having t upp rtin wheels provide amethod of grinding hollow articles to 24, 26, 28 and a grinding wheel30. Preferably t a t f-r91111dng35, Anuther j i; i the remainder of theinternal stock removal ccto provide a method of prcd'acing hollowarticles. WIS On this machin? and the grinding Wheel having uniform wallthickness and smooth surdesirably 0f finer grain a the nding faces ofaccurate size both externallyaincl inwheel 6 o otherwise produces a finternally. According to Fig. 5, the article is polished or To thgge endsand 3150 improve generally buifed externally, removing'all marks fromthe upon methods oi this character, the invention exterior, by a cnterle in in m h ne h vconsists in the various matters hereinafter deinga polishing wheel 32, a regulating wheel 34, scribed and claimed. In itsbroader aspects, and a work support 36. Of course, smaller in- 55crements of grinding. could be given the piece if any out-of-round ormarks still remained and the alternation could be continued as long asneeded.

The applicants alternate grinding of outer and inner surfaces is to bedistinguished from mere successive grinding of such surfaces. Byalternation, each kind of grinding is followed by that kind whichprecedes it, as day follows night and night follows day. There is agrinding operation of one kind intervening between two like grindingoperations of another kind. The first of the like-operations on onesurface does not bring that surface to final size but leaves stock fora. corrective operation which is only repeated after stock has beenremoved from the other surface by the intervening operation. Thus anydistortion of the first surface indirectly resulting from theintervening grinding operation on the other surface is not irrevocablyimparted to the first surface without possibility of correction.

We claim:

1. The method of machining a hollow article to counteractout-of-roundness produced by stock removal, hich consists in alternatelyremoving stock from the exterior and interior surfaces to graduallybring the article to desired size and wall thickness; scribed.

2. The method of machining a hollow article, which consists in passingthe article through two different grinding machines, one operating onthe exterior and another on the interior of the article, and repeatingthe operation on the surface other than the last one treated to bringsuch surface to final size after the release of strains in the previousgrinding; substantially as described.

3. The method of machining a hollow article, which consists in grindingthe outer surface of the article part way to size on an externalgrinding machine, then transferring the article to a plurality ofrotating supporting wheels and grinding the internal surface part way tosize while the article is rotatably supported, and then repeating theoperations; substantially as described.

4. The method of machining a hollow article,

which consists in rotatably supporting the article on a plurality ofwheels while grinding the inner surface, transferring the article to anexternal grinding machine and grinding the outer sur-- face, andtransferring the article to a plurality substantially as deof wheels forfurther grinding on the inner surface; substantially as described.

The method of treating hollow articles, which consists in rough grindingone surface, rough grinding the other surface, and finish grinding saidone surface; substantially as described.

6. The method of treating hollow articles, which consists in roughgrinding the outer surface, rough grinding the inner surface, finishgrinding the outer surface, and finish grinding the inner surface;substantially as described.

7. The method of treating hollow articles, which consists in roughgrinding the outer surface, rough grinding the inner surface, finishgrinding the outer surface, finish grinding the inner surface, andpolishing the outer surface; substantially as described.

8. The method of treating hollow articles, which consists in removingstock from the outer surface but interrupting such removal of stockbefore final size is reached, then removing stock from the innersurface, and then removing more stock from the outer surface to' bringit to size and shape after release of stains in the article due to theprevious operations; substantially as described.

9. The method of treating hollow articles, which consists ,in removingstock from the inner surface, then removing stock from' the outersurface, and then removing stock from the inner surface to produce thedesired internal diameter; substantially as described.

10. The method of machining a hollow article, which consists in firstgrinding the outside surface part way to final size while rotatablysupporting the article by its outer surface, then grinding the internalsurface while rotatably sup-

